• Journal of Korean Port Research
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• v.13 no.1
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• pp.123-132
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• 1999

It is very important to quantitatively assess the movement of sea water and pollutant dispersion before or after constructing shore structures such as breakwater considering marine environment and long-term utilization of those structures. This assesment is possible through the use of simulation models designed to predict water movement and pollutant dispersion in a certain area. In this study the numerical computations were carried out to predict the sea water quality in the Ilgwang Harbor located at the east coast of Pusan. The flow patters were investigated before and after the development of Ilgwang Harbor. The computational models adopting ADI Method (Alternating Direction Implicit Method) were used here and were already verified from the previous studies. As a results of this study the tidal exchange in Ilgwang Harbor after development proved to be worse due to the increased semi-enclosed at the harbor limit. In order to improve the water quality of this area after development a new method was proposed to improve water quality in the semi-enclosed bay by creation and control of tidal residual currents. For this purpose the unsymmetric structures so called bottom roughness were introduced in this study. The simulation was carried out on the basis of the study by Komatsu et. al. and Gug and we made a conclusion that it is possible to generate a new tidal residual current and to increase the tidal exchange by application of bottom roughness arrangement.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.18 no.2
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• pp.137-146
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• 2006

This is the second of a two-part paper which describes comparison of reliability design methods by application to Donghae Harbor Breakwaters. In this paper, Part 2, we deal with sliding of caissons. The failure modes of a vertical breakwater, which consists of a caisson mounted on a rubble mound, include the sliding and overturning of the caisson and the failure of the rubble mound or subsoil, among which most frequently occurs the sliding of the caisson. The traditional deterministic design method for sliding failure of a caisson uses the concept of a safety factor that the resistance should be greater than the load by a certain factor (e.g. 1.2). However, the safety of a structure cannot be quantitatively evaluated by the concept of a safety factor. On the other hand, the reliability design method, for which active research is being performed recently, enables one to quantitatively evaluate the safety of a structure by calculating the probability of failure of the structure. The reliability design method is classified into three categories depending on the level of probabilistic concepts being employed, i.e., Level 1, 2, and 3. In this study, we apply the reliability design methods to the sliding of the caisson of the breakwaters of Donghae Harbor, which was constructed by traditional deterministic design methods to be damaged in 1987. Analyses are made for the breakwaters before the damage and after reinforcement. The probability of failure before the damage is much higher than the allowable value, indicating that the breakwater was under-designed. The probability of failure after reinforcement, however, is close to the allowable value, indicating that the breakwater is no longer in danger. On the other hand, the results of the different reliability design methods are in fairly good agreement, confirming that there is not much difference among different methods.

• Journal of the Korean Association of Geographic Information Studies
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• v.10 no.2
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• pp.1-10
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• 2007

The tendency of erosion and accretion of the coast has occurred by the wanton development of a shore so that establishing the plans of nature preservation and development according to shoreline change is in demand. In this study, six DGPS positioning are executed in the periodic interval of about 2 months to choose coastal area of Gangnung, Gangwon-do and the observation data which is post-processed about 50cm accuracies on the Gangnung regular service is compared with digital map in 1998 and digital chart in 2006. Comparing DGPS values with shoreline of digital map, we know that erosion has occurred locally around training dike placed in Gangmun harbor and in southern Namhangjin, many accretions has happened near the breakwater of Namhangjin region and partial accretion is occurring in the other area. Therefore DGPS which is an acquisition method suitable for GIS data input is in use to collect the horizontal data and it could be used effectively to measure the shoreline change of time series through the long-term continuous observation by the coastal development.

• Journal of Navigation and Port Research
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• v.29 no.7
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• pp.627-634
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• 2005

Gunsan-Janghang Harbor is located at the mouth of Gum River, on the central west coast of Korea The harbor and coastal boundaries are protected from the effects of the open ocean by natural coastal islands and shoals due to depositions from the river, and two breakwaters. The navigation channel commences at the gap formed by the outer breakwater and extends through a bay via a long channel formed by an isolated jetty. For better understanding and analysis of wave transformation process where a wide coastline changes appear due to on-going reclamation works, we applied the spectral wave model including wind effect to the related site, together with the energy balance models. This paper summarizes comparisons of coastal responses predicted by several numerical wave predictions obtained at the coastal waters near Gunsan-Janghang Harbor. Field and numerical model investigations were initially conducted for the original navigation channel management project. We hope to contribute from this study that coastal engineers are able to use safety the numerical models in the area of port and navigational channel design.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2010.10a
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• pp.53-54
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• 2010

국내에서 소규모 어항의 재개발에 관광객 유치를 위한 친환경적인 기술의 적용이 본격화되고 있다. 항내수질 개선이라는 목적 하에서 외곽시설인 방파제의 선택은 항내 정온과 제체 안정성의 확보가 전제되어야 한다. 따라서 본 연구에서는 친환경방파제인 슬릿방파제의 수리특성을 파악하기 위한 수리모형실험을 수행하고 그 결과를 이용하여 파랑변형 및 유동 실험을 수행하였다. 현장 적용성 확인을 위하여 선정된 구조라항은 우리나라 남해의 소규모 어항으로, SSE, S, SSW파향에 영향을 받는 지역으로, 슬릿방파제를 적용한 결과 제체안정성과 항내 정온도가 확보되는 것으로 나타났다. 이는 슬릿방파제의 특징으로 장주기파의 통과율이 뛰어나다는 점과 소파효과라는 1차적인 목적과 항만 및 연안수역에서 해수교환의 향상이라는 2차적인 목적을 동시에 만족하는 것으로 나타났다.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.44 no.3
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• pp.207-217
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• 2008

Costal regions in Korea often suffer severe damages due to wave-induced disasters, storm surge disasters and so on. therefore, many engineers and researchers have devoted their energy to prevent these costal disasters. The development of artificial reefs including sunken vessels is one of their remarkable achievements and various kind of these artificial upwelling structures have been designed and applied. However, the flow characteristics around a Tetrapod under the water has not been investigated experimentally. So in this article, in uniform flow of circulating water channel and some different velocities, PIV measurement has been conducted on the flow characteristics behind a Tetrapod. The results were analyzed on the flow characteristics of both cases of a Tetrapod. Therefore, it can be concluded that the both cases have its own distinctive flow characteristics behind the bluff body; Case A has an steep upstream flow pattern. On the contrary, Case B has an developed downstream flow pattern in the near wake of the Tetrapod. The velocity gradient at position x=150mm of Case-A appears gently up and down But, the velocity gradient at the same position of Case-B appears better highly up and down.

• Journal of Korean Society of Rural Planning
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• v.10 no.4 s.25
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• pp.45-54
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• 2004

In this study, the actual states and cases utilizing lake dykes were investigated focusing on large-scale reclamation project in domestic and instances in advanced foreign countries. The attitudes investigation concerning lake dykes utilization was performed to residents in-and-around Saemangeum. According to the research result, in domestic the utilization of lake dyke have not attracted attention because maximizing land use, which was the primary purpose of reclamation project at the early stage, has been emphasized so far. The advanced foreign countries, however, not only make use of farmland, but also develop activities employing lake dykes. According to the result of an analysis for local residents' attitudes, they want to be used Saemangeum lake dykes as a multifunctionality facilities performing a role of environment friendly equipment as well as a breakwater. They also require further investigation and to be introduced new system far utilizing as a multifunctionality facilities. Recently, green tourism is getting attention more and more owing to laying stress on balanced development of country and improvement on life quality of rural residents and launching five days in duty. It is believed that on this favorable trend lake dykes an be employed as a primary tourism resource if its utilization is developed actively.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.44-57
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• 2010

The purpose of this paper is to introduce case studies on 2 projects for the construction of port facilities in Colombo, Sri lanka. In Queen Elizabeth quay development project in 2000, the damage at the bottom of steel tubular piles were occurred when piles were driven into subsoil for piled wharf structure in Stage 1. In order to prevent same incident in Stage 2 & 3, the pile driveability analysis were executed by dynamic formulas, analysis program, test driving and pile load tests. Through pile driveability analysis, prevention plans were proposed. In Colombo port expansion project in 2008, the mv method was applied to predict a primary consolidation settlement of a subsoil under a breakwater in the calculation stage. The $m_v$ was estimated from results of cone penetration tests and the final settlement by consolidation was calculated with it.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.12 no.4
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• pp.181-189
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• 2000

A weakly nonlinear mild-slope equation has been derived directly from the continuity equation with the aid of the Galerkin's method. The equation is combined with the momentum equations defined at the mean water level. A single component model has also been obtained in terms of the surface displacement. The linearized form is completely identical with the time-dependent mild-slope equation proposed by Smith and Sprinks(1975). For the verification purposes of the present nonlinear model, the degenerate forms were compared with Airy(1845)'s non-dispersive nonlinear wave equation, classical Boussinesq equation, andsecond¬order permanent Stokes waves. In this study, the present nonlinear wave equations are discretized by the approximate factorization techniques so that a tridiagonal matrix solver is used for each direction. Through the comparison with physical experiments, nonlinear wave model capacity was examined and the overall agreement was obtained.

• Journal of Ocean Engineering and Technology
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• v.20 no.4 s.71
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• pp.58-63
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• 2006

When the costal zone surrounded by a breakwater has a narrow vertical opening, currents in the vicinity of a narrow entrance can result in a jet flow, coinciding with the tide. Such a Tidal-Jet Generator(TJG) can change the water mass distribution and transport processes in the domain of influence of the jet. Also, it can decrease the residual time of them. In the present study, the water purification utilizing tidal jets in the coastal zone over constant bathymetry are estimated numerically, using a finite-difference numerical scheme, named the NS-MAC-TIDE method, which isbased on the fully 3D Navier-stokes(NS) equations. The shear velocity near the inlet of the TJG are predicted from the flow field simulation, and are assessed qualitatively with the development of scouring or sediment that is caused by the change of diffusion or sweeping flowup from the seabed of sediment particles. Finally, through solving a transport equation of concentration, the residual time related on mass transport processes and the flushing mechanism for water purification are investigated.